The present invention relates generally to optical edge connectors, and more particularly to optically coupling optical devices mounted on planar substrates oriented orthogonally to each other.
The desirability of using optical systems in high-volume, high-speed signal communication environments is well established despite not being used industry wide. Advances made in processor technology to increase clock speed and data throughput also entails substantially greater bandwidth demands on intra-system communication systems. Thus, further system development is needed to meet the demands of computationally-intensive applications.
Typically, a system having multiple computing components is mounted in a cabinet structure including a box having multiple internal slots. Within the cabinet, components are mounted on printed circuit boards (PCBs); each PCB including a planar substrate having pathways coupling components together. In optical systems, these pathways are waveguides that direct optical signals. Together, the PCBs in the cabinet define intersecting planes orthogonal to a backplane, which may or may not be another PCB.
When optical PCBs are employed, there is the need to optically couple components on intersecting boards, which requires a system for causing an optical signal to “turn a corner.” FIG. 1a illustrates this need where PCB A and PCB B are connected in a conventional backplane orientation to backplane 100. One type of optical edge connector 102 suitable for this configuration can be seen in both FIG. 1a and FIG. 1b. For the purpose of the present description, the y-axis is defined by the longitudinal axis of the PCBs. Thus, in backplane orientations generally, the longitudinal axis is collinear with the insertion axis of the PCBs into the cabinet and the axis of connection of the optical fibers in and out of the cabinets. The x-axis is defined by the axis of connection of the optical fibers on the backplane, shown in FIG. 1b as a second PCB 104. The intersection of the two planes defines a transverse z-axis. Thus, the x and y-axes are perpendicular to each other and are orthogonal to the z-axis.
The optical edge connector 102 provides a system to interconnect the optical fibers in the backplane, here PCB 104, with the optical fibers of PCB 106 using an optical waveguide array 108, thereby coupling optical devices (not shown). The waveguide array 108 includes multiple two-dimensionally integrated cores 109, with each integrated core 109 including a vertical core 119 and a horizontal core 129, the integrated cores being redirected by a mirror 110 positioned at a 45 degree angle to the surface of PCB 104. Thus, optical signals inputted from the optical fibers of PCB 104 are redirected 90 degrees from vertical cores 119 to horizontal cores 129 positioned parallel to the longitudinal axis of PCB 104.
However, for system designs placing a high premium on packaging density and achieving minimum source-to-destination propagation delay times, optical edge connector 102 is insufficient. It is well known that the packaging density is physically limited by the thickness of the components attached to the PCBs. Yet it is also known that, the closer the components can be placed together, the lower the latency in communication. By being limited to the conventional backplane configuration, system designs attempting to minimize the distance between a maximum density of components are thus hampered by the thickness of each component.
Thus, there is a need for an optical edge connector capable of connecting hybrid PCBs oriented in configurations that reduce packaging density and achieve a reduction in source to destination propagation delay times.